// Jubatus: Online machine learning framework for distributed environment
// Copyright (C) 2011 Preferred Infrastructure and Nippon Telegraph and Telephone Corporation.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

#include "norm_l2.hpp"

namespace jubatus {
namespace storage {

norm_l2::norm_l2(){
}

norm_l2::~norm_l2(){
}

void norm_l2::clear(){
  sq_norms_.clear();
}

void norm_l2::notify(const std::string& row, float old_val, float new_val){
  float& v = sq_norms_[row];
  v -= old_val * old_val;
  v += new_val * new_val;
}

float norm_l2::calc_norm(const std::string& row) const{
  pfi::data::unordered_map<std::string, float>::const_iterator it = sq_norms_.find(row);
  if (it == sq_norms_.end()){
    return 0.f;
  }
  return std::sqrt(it->second);
}

}
}
